1. Field of the Invention
The present invention relates to a grinding wheel form defining device for defining the cross-sectional form of a grinding wheel (hereinafter referred to as "a grinding wheel form"), including the axis of the grindstone, of a grinding wheel for grinding workpieces.
2. Description of the Related Art
FIG. 1 is a block diagram of a conventional grinding wheel form defining device. This grinding wheel form defining device is designed such that an operator controls a grinding wheel form defining device 5, comprising a grinding wheel basic form storing section 8 and a grinding wheel basic form selecting section 13, using an operation panel 3 comprising a CRT 1 capable of graphic display, a keyboard 2, a display control section 7 and an input control section 4.
Particularly, when various types of input data and operation commands SB are input from the keyboard 2 to the input control section 4 by the operator, the input control section 4 converts the various types of the input data and the operation commands SB into a grinding wheel basic form selection command SM and outputs the same to the grinding wheel basic form selecting section 13. The grinding wheel basic form storing section 8 stores a plurality of types of grinding wheel basic forms which are the simple two-dimensional patterns of the typical grinding wheel forms. The grinding wheel basic form selecting section 13 reads out a grinding wheel basic form SI based on the grinding wheel basic form selection command SM from the grinding wheel basic form storing section 8 and sends without alteration the selected grinding wheel basic form SI to a process simulation display section or to a part program generating section as a grinding wheel form SL. Also, the grinding wheel basic form selecting section 13 generates a display control command SE and sends the same to the display control section 7 in order to display the selected grinding wheel basic form SI on the CRT 1. The display control section 7 converts the display control command SE into a display output command SA, and sends the resulting display output command SA to the CRT 1 which displays on a screen the grinding wheel basic form selected by the grinding wheel basic form selecting section 13.
FIGS. 2A, 2B and 2C show examples of the grinding wheel basic form stored in the grinding wheel basic form storing section 8. FIG. 2A shows a plain type grinding wheel 31. FIG. 2B shows an angle type grinding wheel 32. FIG. 2C shows a grinding wheel 33 used for internal grinding. Since these basic forms 31 to 33 are the patterned ones, they can be defined easily by the input of only basic data such as an external diameter, a width of the grinding wheel or the like.
FIGS. 3 and 4 are respectively block diagrams of an automatic programming apparatus 14 and a numerical control (NC) grinding machine 15, each of which incorporates the aforementioned grinding wheel form defining device 5. In the automatic programming apparatus 14 shown in FIG. 3, the grinding wheel form SL defined by the grinding wheel form defining device 5 is read in a part program generating section 9 which analyzes the grinding wheel form SL to thereby generate a part program for dressing. In the NC grinding machine 15 shown in FIG. 4, the grinding wheel form SL defined by the grinding wheel form defining device 5 is read in a process simulation display section 11 which analyzes the grinding wheel form SL to thereby perform grinding simulation.
The cross-sectional form (hereinafter referred to as "a workpiece form") of a workpiece which is the final form in the grinding process, prepared by an automatic programming apparatus or the like, is generally defined by either of the following methods:
(1) A method which uses one-dimensional form elements such as a straight line, a taper, an arc or the like. PA1 (2) A method which uses two-dimensional form elements such as a rectangle, a trapezoid, rounded trapezoid or the like.
In these methods, complicated workpiece forms can be easily defined on the basis of the dimensions or the like described on the process drawings. For example, in the case of a workpiece form 20 shown in FIG. 5, an objective workpiece form can be defined using the two-dimensional form elements, i.e., four rectangles and two rounded trapezoids, and by designating the dimensions for each form element.
The conventional grinding wheel form defining device 5 has no function for defining the workpiece form, unlike the automatic programming apparatus, because the dimensions of the grinding wheel form are not described on the process drawing and because the workpiece form defining method cannot be utilized to define the grinding wheel form without being changed. Therefore, in a case where the grinding wheel form used in an actual grinding process is a complicated one which is not stored in the grinding wheel basic form storing section 8, the grinding wheel form defining device 5 cannot define the grinding wheel form accurately. In the grinding process in which, for example, a machined surface 22 of the workpiece form 20 as shown in FIG. 5 is ground in a one plunge cutting process (hereinafter referred to as "a total form plunging"), a complicated grinding wheel form such as that shown in FIG. 6A is required. Thus, the conventional grinding wheel form defining device 5 temporarily selects the plane type grinding wheel 31 as shown in FIG. 2A and defines it as the grinding wheel form. In the simulation of the total form plunging performed at that time by the NC grinding machine 15, the grinding wheel and the workpiece are displayed in a collided state as shown in FIG. 6B. This lessens the advantage of the simulation such as the interference checking function.
In the automatic programming apparatus 14, since the automatic programming function cannot be used to generate the part program for the dressing which uses a single point diamond, the operator must generate the part program for dressing by referring to the process drawing. This leads to generation of programming errors and requires a large amount of time.